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Impact of changing over of insecticide from synthetic pyrethroids to DDT for indoor residual spray in a malaria endemic area of Orissa, India.

Sharma SK, Upadhyay AK, Haque MA, Tyagi PK, Kindo BK - Indian J. Med. Res. (2012)

Bottom Line: ACM was effective in killing An. culicifacies on mud and wooden sprayed surfaces and maintained effective bioefficacy ranging from 92 to 100 per cent up to five months, whereas DDT failed to achieve effective mortality in An.culicifacies.However, there was significant decline in the density of An.culicifacies in ACM and DDT areas in comparison to ITNs/LNs.There was 61 per cent reduction in the slide positivity rate in ACM area in comparison to 48 and 51 per cent in DDT and ITN/LNs areas, respectively.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Malaria Research, Field Station, Rourkela, India.

ABSTRACT

Background & objectives: Development of insecticide resistance in malaria vectors has been a major problem for achieving effective vector control. Due to limited availability of insecticides, the only option is management of resistance by judiciously using the insecticides and rotating them to maintain their effectiveness. This study was carried out in a malaria endemic area of Sundergarh district in Orissa where synthetic pyrethroids (SP) were in use for the last couple of years. The change-over from SP to DDT was done in one arm of study, and the other two arms remained on SP and insecticide-treated nets (ITN). Entomological and parasitological monitoring was done to assess the impact.

Methods: The study design comprised of three arms (i) two rounds of indoor residual spraying (IRS) with DDT 1g/m(2) as a change-over insecticide in areas previously under synthetic pyrethroids; (ii) two rounds of IRS with synthetic pyrethroid (alphacypermethrin, ACM) @ 25 mg/m(2) ; and (iii) an unsprayed area under ITN/long lasting insecticide nets (LNs). Indoor residual spraying was undertaken under strict supervision to maintain quality and coverage. Contact bioassays were conducted to know the persistence of insecticide on sprayed surfaces and adult vector density was monitored in fixed and randomly selected houses. Malaria incidence was measured through fortnightly domiciliary surveillance under primary health care system in all the study villages.

Results: The insecticide susceptibility tests showed that An.culicifacies was resistant to DDT but susceptible to malathion and ACM. However, An. fluviatilis was susceptible to all the three insecticides. ACM was effective in killing An. culicifacies on mud and wooden sprayed surfaces and maintained effective bioefficacy ranging from 92 to 100 per cent up to five months, whereas DDT failed to achieve effective mortality in An.culicifacies. However, there was significant decline in the density of An.culicifacies in ACM and DDT areas in comparison to ITNs/LNs. There was 61 per cent reduction in the slide positivity rate in ACM area in comparison to 48 and 51 per cent in DDT and ITN/LNs areas, respectively. The adjusted incidence rate of malaria cases per 1000 population in three study areas also showed significant declines within each group.

Interpretation & conclusions: The present findings show that the change-over of insecticide from synthetic pyrethroids to DDT brings about the same epidemiological impact as envisaged from continuing SP spray or distributing insecticide treated nets/long-lasting insecticidal nets provided there is a good quality spray and house coverage.

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Density of An. culicifacies in houses sprayed with alphacypermethrin (ACM), DDT and houses with ITN/LNs during intervention period. First round of IRS was carried out in November-December 2009 and second in May 2010.
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Figure 1: Density of An. culicifacies in houses sprayed with alphacypermethrin (ACM), DDT and houses with ITN/LNs during intervention period. First round of IRS was carried out in November-December 2009 and second in May 2010.

Mentions: Impact on vector density: The first round of spray with ACM and DDT resulted in significant decline in the density of An. culicifacies in comparison to ITNs/LNs (Fig. 1). The density of malaria vector was almost nil in the houses sprayed with ACM. However, after the second round of spray, there was marginal increase in the vector density in ACM and DDT areas. The increase in vector density was also observed in the ITN/LN area.


Impact of changing over of insecticide from synthetic pyrethroids to DDT for indoor residual spray in a malaria endemic area of Orissa, India.

Sharma SK, Upadhyay AK, Haque MA, Tyagi PK, Kindo BK - Indian J. Med. Res. (2012)

Density of An. culicifacies in houses sprayed with alphacypermethrin (ACM), DDT and houses with ITN/LNs during intervention period. First round of IRS was carried out in November-December 2009 and second in May 2010.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3361876&req=5

Figure 1: Density of An. culicifacies in houses sprayed with alphacypermethrin (ACM), DDT and houses with ITN/LNs during intervention period. First round of IRS was carried out in November-December 2009 and second in May 2010.
Mentions: Impact on vector density: The first round of spray with ACM and DDT resulted in significant decline in the density of An. culicifacies in comparison to ITNs/LNs (Fig. 1). The density of malaria vector was almost nil in the houses sprayed with ACM. However, after the second round of spray, there was marginal increase in the vector density in ACM and DDT areas. The increase in vector density was also observed in the ITN/LN area.

Bottom Line: ACM was effective in killing An. culicifacies on mud and wooden sprayed surfaces and maintained effective bioefficacy ranging from 92 to 100 per cent up to five months, whereas DDT failed to achieve effective mortality in An.culicifacies.However, there was significant decline in the density of An.culicifacies in ACM and DDT areas in comparison to ITNs/LNs.There was 61 per cent reduction in the slide positivity rate in ACM area in comparison to 48 and 51 per cent in DDT and ITN/LNs areas, respectively.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Malaria Research, Field Station, Rourkela, India.

ABSTRACT

Background & objectives: Development of insecticide resistance in malaria vectors has been a major problem for achieving effective vector control. Due to limited availability of insecticides, the only option is management of resistance by judiciously using the insecticides and rotating them to maintain their effectiveness. This study was carried out in a malaria endemic area of Sundergarh district in Orissa where synthetic pyrethroids (SP) were in use for the last couple of years. The change-over from SP to DDT was done in one arm of study, and the other two arms remained on SP and insecticide-treated nets (ITN). Entomological and parasitological monitoring was done to assess the impact.

Methods: The study design comprised of three arms (i) two rounds of indoor residual spraying (IRS) with DDT 1g/m(2) as a change-over insecticide in areas previously under synthetic pyrethroids; (ii) two rounds of IRS with synthetic pyrethroid (alphacypermethrin, ACM) @ 25 mg/m(2) ; and (iii) an unsprayed area under ITN/long lasting insecticide nets (LNs). Indoor residual spraying was undertaken under strict supervision to maintain quality and coverage. Contact bioassays were conducted to know the persistence of insecticide on sprayed surfaces and adult vector density was monitored in fixed and randomly selected houses. Malaria incidence was measured through fortnightly domiciliary surveillance under primary health care system in all the study villages.

Results: The insecticide susceptibility tests showed that An.culicifacies was resistant to DDT but susceptible to malathion and ACM. However, An. fluviatilis was susceptible to all the three insecticides. ACM was effective in killing An. culicifacies on mud and wooden sprayed surfaces and maintained effective bioefficacy ranging from 92 to 100 per cent up to five months, whereas DDT failed to achieve effective mortality in An.culicifacies. However, there was significant decline in the density of An.culicifacies in ACM and DDT areas in comparison to ITNs/LNs. There was 61 per cent reduction in the slide positivity rate in ACM area in comparison to 48 and 51 per cent in DDT and ITN/LNs areas, respectively. The adjusted incidence rate of malaria cases per 1000 population in three study areas also showed significant declines within each group.

Interpretation & conclusions: The present findings show that the change-over of insecticide from synthetic pyrethroids to DDT brings about the same epidemiological impact as envisaged from continuing SP spray or distributing insecticide treated nets/long-lasting insecticidal nets provided there is a good quality spray and house coverage.

Show MeSH
Related in: MedlinePlus